Cattle are prime targets for many types of viral, bacterial, and parasite infections. Modern production practices, such as weaning, shipment of cattle, inclement weather, and nutritional needs within the beef and dairy industries may also serve as risk factors that potentiate the incidence of disease. Bovine respiratory disease (BRD), or bovine respiratory diseases complex, as it is often referred to, occurs in both dairy and beef cattle and is one of the leading causes of economic loss to the cattle industry throughout the world. These losses are due to morbidity, mortality, reduced weight gains, treatment and prevention costs, loss of milk production, and negative impacts on carcass characteristics.
The pathogenesis of BRD is thought to arise from numerous environmental and physiological stressors, mentioned above, coupled with infectious agents. Mannheimia (Pasteurella) haemolytica, Pasteurella multocida and Histophilus somni (formerly Haemophilus somnus) are considered part of the normal flora of the bovine upper-respiratory tract. Conversely, the lower respiratory tract is a relatively sterile environment that is maintained by numerous immunological pathways aimed at the prevention of microbial entry. When cattle are subjected to environmental and physiological stressors, the animal's innate and acquired immune functions are compromised thereby allowing these aforementioned organisms to proliferate and subsequently colonize the lower respiratory tract. Various bovine viruses are known to have immunosuppressive effects in the lung, such as infectious bovine rhinotracheitis virus (IBRV, IBR, or BHV 1), bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), and parainfluenza type 3 virus (PI3). However, Mannheimia haemolytica is by far the most prevalent bacterial pathogen among cases of BRD.
Current prevention and treatment of BRD consists of antibiotic administration to populations of cattle upon arrival at feedlots (i.e. metaphylaxis), antibiotic therapy for sick cattle, and vaccination against BRD viruses and bacteria including M. haemolytica. 
There are different reasons why current vaccination programs and pharmaceutical therapies are not optimal to control BRD in cattle today. First, the host defense system plays a major role in combating infectious disease in cattle. Conventional treatments include the administration of antibiotics to treat or control bacterial infections. However, there are no approved pharmaceutical treatments available against viral infections. With BRD, in most cases not only is there a bacterial infection but also a viral infection. Second, timing of vaccination is often sub-optimal. For a respiratory vaccine to be optimally effective the product should be administered 2-4 weeks prior to stress or shipment and this is typically not feasible in commercial cattle production. The vaccines are either administered too early or too late to be optimally effective.
Therefore a need exists for a method to stimulate the immune system and build an offensive response to reduce or eliminate disease causing organisms. It is important that this method is easy to administer, works alone or in combination with vaccines or helps to make such vaccines more effective, has a longer duration or that does not require added injections to maximize immunity. The present invention provides a method of eliciting a non-antigen-specific immune response in the bovine species that is easy to administer, works alone or in combination with vaccines, induces a protective response against one or more infectious agents.